The dwarf planet Pluto and most of its moons were named after the Roman god of death and his grim entourage, so it would be ironic if they turned out to be the only objects in the solar system outside of Earth that contained life. It would also be a little surprising, considering their distance from the Sun, but several recent scientific studies have indirectly raised the possibility.
We've recently discussed the theory that Pluto's plate tectonics, if they turn out to exist, may indicate a liquid underground ocean that could support life. Now American astrophysicist Alyssa Rhoden has suggested that Charon, too, may have had a liquid underground ocean at one time—and she has developed a system of analyzing cracks in the lunar surface that, once we've actually had a chance to look at Charon's surface, may give us a better indication of how old and how large that underground ocean may have been, as well as its composition.
We'll get our first opportunity to apply Rhoden's theory in July 2015, when NASA's New Horizons probe takes the first high-resolution photographs of Pluto and Charon—and gives us some understanding of Charon's surface features. Rhoden doesn't think it's likely that Charon has an underground ocean now, given its current orbit (and the low likelihood that this orbit could produce enough stress to make Charon geologically active), but the outer solar system has proven itself to be full of surprises. The surface of Charon may turn out to be one more.